The invention concerns apparatus for correlating the respiratory and cardiac cycles, i.e., apparatus capable of recognizing the moment at which the patient (or the animal) is simultaneously at a precise and chosen period in the progress of his respiratory cycle and at a precise and chosen period in the progress of his cardiac cycle. At this moment, the apparatus yields a signal which can control any selected apparatus, and particularly, but not exclusively, an automatic injector, controlled by the electrocardiagram, for measuring the cardiac output.
The correlation between the respiratory and cardiac cycles could be recognized by a human operator, but, the apparatus of this invention, besides offering the advantages inherent in an automatic mechanism, is equipped with improvements that are only possible under automation, and certain ones of these improvements make it possible for the apparatus to function in pathological cases that are beyond the capabilities of a human operator.
The use of the apparatus of the invention is not, of course, limited to the measurement of cardiac output. On the contrary, it extends to mechanisms used in radiology, and, in particular, pulmonary radiography of infants or patients in coma, and to angiocardiography.
In pulmonary radiography, it is necessary that certain radiological negatives of the pulmonary apparatus be taken at the moment of expiration or at the moment of inspiration. It is an object of the apparatus of this invention to fill this need.
Angiocardiography is the radiological method which reveals the cardiac cavities or the vessels and the blood which circulates there by means of injection of a substance which is opaque to X-rays. The patient undergoing the examination has a catheter placed in his vein, which makes it possible to inject the opaque substance where desired. Thereupon, a series of negatives is made as needed.
The results of these examinations depend upon the respiratory or cardiac cycles. It is thus important that the taking of these negatives be automatized in relation to these two functions, which makes it possible to obtain negatives relating to various moments in these cycles. The apparatus according to this invention was, again, designed in order to fill this need.